©2003 algirdas pakštas sisteminis tinklų planavimo metodas bei reikalavimų analizės rolė (nuo...

©2003 Algirdas PakštasSisteminis tinklų planavimo metodas bei reikalavimų analizės rolė (nuo meno link inžinerijos)

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Infobalt’03 SeminarasInfobalt’03 SeminarasSisteminis tinklSisteminis tinklųų

planavimo metodas bei planavimo metodas bei reikalavimreikalavimųų analizanalizėės rols rolėė

(nuo meno link in(nuo meno link inžžinerijos)inerijos)Prof.DrTech. Algirdas PakštasLondon Metropolitan University

Department of Computing, Communications Technology and Mathematics

[email protected],[email protected]

Infobalt 2003, Vilnius, 2003m. spalio 23d.


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Abstract:Abstract: Tutorial looks at the problem of network planning when network

is considered not as collection of separate components but as a system. Tutorial consists of two parts. The first part of the Tutorial is devoted to the general overview of the network analysis and design processes. Network services and services-based networking are discussed. Systems and network services are presented with more details. Especial attention is devoted to characterizing of services including discussion on service requests, service offerings, service performance requirements, service metrics, as well as reservations and deadline scheduling. The second part of the Tutorial is focusing on the concepts of requirement analysis. Description of the background for requirement analysis is followed by the discussions on User Requirements, Application Requirements (types of applications, reliability, capacity, delay, application groups), Host Requirements (types of host and equipment, performance characteristics, location information), and Network Requirements (existing networks and migration, functional requirements, financial requirements, enterprise requirements).


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Biography:Biography: Prof. Algirdas Pakstas received his M.Sc. in Radiophysics

and Electronics in 1980 from the Irkutsk State University, Ph.D. in Systems Programming in 1987 from the Institute of Control Sciences. Currently he is with the London Metropolitan University, Department of Computing, Communications Technology and Mathematics where he is doing research in the area of Communications Software Engineering and is teaching courses "Network Planning and Management" and "Computer Systems and Networks". He is active in the IEEE Communications Society Technical Committees on Enterprise Networking, Communications Software and Multimedia Communications. He has published 3 research monographs (2 authored and 1 edited) and more than 140 other publications. He is a Senior Member of the IEEE and a Member of the ACM and the New York Academy of Sciences. He is currently a member of the Editorial Boards of the following journals and magazines: IEEE Communications Magazine, Cybernetics and Systems Analysis, Journal of Information and Organizational Sciences.


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PART 1: OUTLINEPART 1: OUTLINE A Systems Approach to Network

Design Introduction - Traditional Network Design The Analysis and Design Processes Network Services and Services-Based

Networking Systems and Network Services

Systems Network Services

Characterizing Services Service Requests Service Offerings Service Performance Requirements Service Metrics Reservations and Deadline Scheduling


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Introduction - Traditional Introduction - Traditional Network DesignNetwork Design• A kind of art

– Evaluating and choosing network technologies

– Knowing how technologies, services and protocols work

– Experience in what works and what does not


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Introduction - Traditional Introduction - Traditional Network DesignNetwork Design• As in other types of art

– Success greatly depends on the person(s) who is/are doing it

– Designs are rarely reproducible

• Traditional network design is based on developing a set of pragmatic rules e.g.

• “80/20 rule”

• “bridge when you can, route when you must”

• “throw bandwidth at the problem”


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Introduction - Traditional Introduction - Traditional Network DesignNetwork Design• It was focusing primarily on capacity planning

• Pragmatic rules worked well with limited choice of technologies, interconnection strategies, routing protocols

• Times have changed– We must adapt design process to the variety of options– Many new types of services can be offered to the users– Additionally to the capacity planning we need to

consider optimization of the delay in the network– Providing reliability is more than just redundant paths in

the network or resilient routing prtocols


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The Analysis and Design The Analysis and Design ProcessesProcesses

• Network analysis and design is a combination of– Design goals– Trade-offs

• Balance between architecture and function

• Design goals could be such as– Minimizing network costs– Maximizing performance

• Trade-offs– Cost vs. performance– Simplicity vs. function– Many ways to achieve design goals - rarely single “right”

one• There are often many wrong ways...


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The Analysis and Design The Analysis and Design ProcessesProcesses

• Components of the Analysis and Design Processes (listed consequently):– The Systems Approach to Design

– Requirement Analysis

– Flow Analysis

– Logical Design

– Physical Design

– Addressing and Routing


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Network Services and Network Services and Services-Based Services-Based NetworkingNetworking• There has been significant effort to define

and specify “services” in the ISO/OSI model

• It is a new approach to looking at networking from the services prospective in the IP-world

• “Services-Based Networking is the concept of developing network designs that take into account network services and service support”


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Network Services and Network Services and Services-Based Services-Based NetworkingNetworking

Generations of the network servicesGeneration Time Frame CapabilityFirst 1960s-mid-1980s Basic

connectivity/ interoperabilitySecond mid-1980s- Performance (IP early/mid-1990s forwarding rates)Third (current) mid-to-late 1990s Network

Services (levels of network performance and function)Fourth 2000-2010 Self-configuration/ administration


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Systems and Network Systems and Network Services: SystemsServices: Systems

“A network system is the set of components that work together to support or provide connectivity, communications, and network services to users of the system”

Generic components of a System

| User | | User |

|Application| |Application|

| Host | ! Host | ---------- ---------- |------(Network)-----|


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Systems and Network Systems and Network Services: Services: SystemsSystems

Traditional View of a System ------------ ------------ | Host | | Host | ------------ ------------

|----- (Network) ---|

Network design have focused on providingconnectivity between hosts

Systems were described as the set (host,network)

and typically did not consider the users or applications

Thus, there is a need to define more precisely the set

(user, application, host, network) Sometime definitions of the “host” and the

“network” are not very much obvious


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Systems and Network Systems and Network Services: Services:

Interfaces and BoundariesInterfaces and Boundaries If the components are known then thethe

boundary condition between them can be set and therefore the interfaces

Example:

User User

Application Application

Host Host

Network

Display ParametersUser Interface

API, QoS, ToS

Drivers, Interfaces


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ATM in Network BackboneATM in Network Backbone Example: The picture below is showing the

ATM as a backbone technology

| User | | User | |Application | |Application | | Host | | Host | ---------- ---------- \-------(x) NETWORK (x)--------| \--[atmX]---[atmX] --/

Here (x) - Router [atmX] - ATM Switch

Here the ATM environment is isolated from the hosts, applications and users by the routers


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“Native” ATM Network“Native” ATM Network Example: The picture below is showing a “native” ATM network in

which ATM is integrated into the host side [User] [User]

[Application] [Application]

--------------------------------(ATM)---------------------------------

[ATM Specific API] [ATM Specific API]

[ATM Device Driver] [ATM Device Driver]

\ [atmX]-[atmX]-[atmX]-[atmX]/

Here [atmX] - ATM Switch Here the ATM is integrated into the host and will

interface directly with the applicaions The system is best described as as the set

(user,application, ATM-specific API, ATM device driver, network)


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Systems and Network Systems and Network Services: Services: ServicesServices

• According to the IETF and ATM Forum– Network Services are sets of network

capabilities that can be configured and managed within the network

– Network Services are defined • as levels of performance and function that are

offered by the network, host, and/or application, to the rest of the system,

• or as sets of requirements that are expected from the network by the end user, application, or host


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• Levels of performance are described by the performance characteristics, e.g.

– capacity– delay– reliability

• Functions include– security– accounting– billing– scheduling– management


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• Network services: groups of characteristics and levels

Service Characteristics Characteristic A \ Characteristic B }-> Service Level Characteristic C / Level A \

… / Level B }-> Network Service | Level C / Description for Design V … /Characteristics used to configure services in network

and as service metrics to measure and verify services


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Systems and Network Systems and Network Services: Services: Service Service CharacteristicsCharacteristics

Service characteristics = Individual network performance and functional parameters Service offering - by the network to the

system Service request - from the network by

users, applications, or hosts Service requirements = characteristics

that are used to gauge the system’s need for services


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Systems and Network Systems and Network Services: Services: Service Service CharacteristicsCharacteristics

Service characteristics and requirements are useful in the network analysis and design processes: In configuring services in network elements

(routers, switches, host operating systems) In providing input into the network design

Need to be described and provisioned end-to-end, at all components between end users, applications and hosts

Service may fail if some components are not capable to support it!


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Systems and Network Systems and Network Services: Services: Service LevelsService Levels

Service requirements or characteristics are grouped together to describe service levels

Easier to configure, measure and verify service level instead of a number of individual service characteristics

Helpful in service accounting and billing Service levels can be described with the help

of Committed Information Rates (CIRs) Classes of Services (CoSs) Types of Services (ToSs) Qualities of Services (QoSs) Custom service levels based on groups of

individual service characteristics depending on technology, protocol, etc.


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Characterizing ServicesCharacterizing Services

Service Requests Service Offerings Service Performance

Requirements Service Metrics Reservations and Deadline

Scheduling


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Characterizing ServicesCharacterizing Services Service RequestsService Requests

Can be distinguished by the degree of predictability: Best-effort (e.g. best-effort

delivery) Specified, i.e. deterministic and

guaranteed


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Best-effort: No control over how network will

satisfy the service request No guarantees are presented Network is not obligated to do more

than try Indicates that the rest of the

system (user, application, host) will need to adapt to the state of the network at any given time


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Best-effort: Expected service for such requests

is unpredictable and variable Such service requests

Either have no performance requirements for the network

Or the requirements are nonspecific Consequently service requests are not

tuned to any specific user or application (i.e. very much universal, generally oriented)


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Specified service requests Are based on some knowledge of or control

over the state of the system Have more stringent service requirements

(i.e. deterministic and guaranteed) than best-effort

To support a deterministic service request by the network the service requirements of the request must be measurable and verifiable

Need for the service metrics


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Specified service requests EXAMPLE:

If service request is made for capacity to be 4-10 Mb/s

Then there must be Way to translate these service requirements

into a service offering from the network Way to measure and/or to derive these

capacity characteristics from the network Statistical method to control the information

flow and the network to keep this service between the targeted 4-10 Mb/s


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Specified service requests Service performance requirements are

usually grouped into service levels Service levels can be the same as

specified service requests And also can be closely related to well-

known service offerings from the network such as

ATM QoS SMDS CoS ...


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Specified service requests Mapping Service Levels to Service Offerings:

Service RequestService Performance Requirements

Service Levels (Groups of Requirements) | | |Service Metrics -------------------------------------------------- | | |

SMDS CoS ATM QoS Frame Relay CIRService Performance Characteristics

Service Offering

SMDS CoS - Switched Multimegabit Data Service Classes of Service

ATM QoS - Asynchronous Transfer Mode Quality of ServiceCIR - Committed Information Rates


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Characterizing ServicesCharacterizing Services Service OfferingsService Offerings

Similarly to the Service Requests the Service Offerings are also grouped as: Best-effort

Specified


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Best-effort Internet is a good example Best-effort service offering is compatible

with the best-effort service request EXAMPLE:

File transfer (via FTP) occurs over IP FTP uses TCP which via sliding window flow

control mechanism adapts to the current state of the network it is operating over

Service requirement from FTP over TCP is best-effort

Service offering from the Internet is best effort During the FTP session the performance

characteristics of the IP network and transport method (TCP) are constantly adapted


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Specified (deterministic and guaranteed) service offerings are: Predictable, bounded, or guaranteed Specified refers to the network’s ability to

offer a measurable and verifiable service Can be low- or high-performance

Specified service does not imply high performance Similarly, ISO 900x quality assurance standards

can not guarantee you a GOOD THING but just a SPECIFIED QUALITY whatever they mean by it!!!


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EXAMPLE of Specified Service : Network to support real-time telemetry data Design goal would be the ability to specify

end-to-end delay and have the network to satisfy this delay request

For example, a service request may be for an end-to-end delay of 25ms, with a delay variation of 400s

This would form the request and the service level (i.e. QoS level) that needs to be supported by the network

The network would then be designed to provide a specified service offering at a QoS level of 25ms end-to-end delay and 400s delay variation

The delay and delay variation would then be measured and verified with service metrics (using tools such as ping or tcpdump, or with custom one)


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Service Requests and Offerings Service Request | | Best-Effort Deterministic/Guaranteed | | | Service Performance

Characteristics/Levels | | | |Service Metrics -------------------------------------------------------- | | | | | Service Performance

Characteristics/Levels | | Best-effort Deterministic/Guaranteed | | Service Offering


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Characterizing ServicesCharacterizing Services Service Performance Service Performance

RequirementsRequirements Service Performance Requirements

Reliability, Capacity and Delay are related to each other

Reliability: Definition by the J.D.McCabe:

“Reliability is a measure of the system’s ability to provide deterministic and accurate delivery of information...”

– IT CAN BE ARGUED THAT RELIABILITY IS ONLY THE GUARANTEE OF ACCURACY WITH NO TIME CONSTRAINTS

– DIFFERENT DEFINITION OF RELIABLITY MAY LEAD TO BUILDING DIFFERENT CONCEPTS WHICH BETTER REFLECT A REAL WORLD VIEW TO THE SYSTEM’S DESIGN


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RequirementsRequirements Capacity

“It is a measure of the system’s ability to transfer information”

This term is often used intechangeably with bandwidth, throughput and goodput

Bandwidth is sometime described as theoretical capacity what is not strictly correct (remember Nyquist’s and Shannon’s equations?)

Throughput is the realizable capacity of the system or its components or elements SONET OC-3c circuit is designed to achieve data

rate 155.52 Mb/s = 3x51.84 Mb/s (i.e. 3xOC-1 circuits)

Practically achievable throughput is ~80-128 Mb/s


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RequirementsRequirements Delay

“It is a measure of the time which is taken for the transmission of the single unit of information (bit, byte, cell, frame, packet) across the system”

Often used are propagation, transmission, queueing, and processing delays

End-to-end and round-trip delays are useful measurements

Delay represents microscopic view of network behaviour

Latency can be defined as an overall delay caused by the application processing and task completion times Latency represents macroscopic view of network

behaviour


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RequirementsRequirements Performance Envelops

Useful for visualizing the regions of performance in which the network will be expected to operate

Service performance requirements can be mapped from the applications onto such environments in order to show relative performance of each application

EXAMPLES: 2-D Service Performance Envelop describing

Capacity, Data Size and End-to-end Delay 3-D Service Performance Envelop including

Reliability


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RequirementsRequirements2-D Service Performance Envelop

describing Capacity, Data Size and End-to-end Delay


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RequirementsRequirements3-D Service Performance Envelop including

Reliability

Note low-performance and high-performance regions!


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Characterizing ServicesCharacterizing Services Service MetricsService Metrics

Service metrics are intended to be measurable

Can be used to establish reference levels (a combination of service metrics for reliability, capacity and delay) for service performance

3 types of reference levels: Service thresholds Service boundaries Service guarantees


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Service thresholds - discriminators used on applications to distinguish between high-performance and low-performance service

Service boundaries - combinations of low- and/or high-performance levels used to predict a service level for an application

Service guarantees - strict performance levels. If they are not met it may cause some type of action from the system (such as policing)


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Reference levels are described in terms of service metrics for the system

EXAMPLE: System using SNMP has MIB variables for each network element We may choose:

A reference level of the amount of the capacity being utilized

A service metric of the number of bytes in or out of each interface of the network elements

MIB variables of ifInOctets and ifOutOctets


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Example of Reference Levels-Service Thresholds

Threshold | App3 App6 | App5 App2 App1 | App4--------------------|---------------> ServiceLow Capacity | High Capacity Threshold Expected/Predicted Application Capacities


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Example of Reference Levels - Boundaries and Guarantees


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Characterizing ServicesCharacterizing Services Reservations and Reservations and

Deadline SchedulingDeadline Scheduling

Some applications may be operating in real-time Session may be not active until time T

Resources for this application are not required until time T and can be used for something else

Application may have a deadline when all tasks must be completed May need prioritizing of the use of

network resources for this application


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Conclusions for PART 1Conclusions for PART 1 It is very important to take a

system’s approach to network design System = (user, application, host,

network) System is offering services to the end

users/customers In order to implement services and

and achieve their characteristics we need to quantify requirements

Requirements Analysis is the next step in the network analysis process: To gather, analyze, and understand the

requirements from the system


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PART 2: OUTLINEPART 2: OUTLINE Requirements Analysis: Concepts

Background for Requirement Analysis User Requirements Application Requirements

Types of Applications Reliability Capacity Delay Application Groups

Host Requirements Types of Host and Equipment Performance Characteristics Location Information

Network Requirements Existing Networks and Migration Functional Requirements Financial Requirements Enterprise Requirements


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Background for Background for Requirement AnalysisRequirement Analysis

Requirement Analysis helps to understand design environment

Consists of Identifying, gathering, and understanding

system requirements and their characteristics Developing thresholds for performance to

distinguish between low- and high-performance services

Determining specified services for the network

Requirement Analysis is fundamental to the network design process but is often overlooked or ignored


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Gathering requirements means talking to users and network personnel and interpreting the results Each user has its own set of requirements Network personnel are often distanced from

the users and do not have clear idea of what users want or need

Thus it is a difficult part of the design process Not doing it may lead to the solutions

which are not those which the users and applications may need


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EXAMPLES: Design is based on a particular technology,

typically on the most comfortable for the designer

Design is based on a particular vendor… This happens due to the budget constraints and

deadlines which are forcing to use familiar, easy to apply technologies

Problem is that such designs are not objective Familiar technologies, protocols or vendors may

be poor choices for that particular environment


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The results of the Requirement Analysis are Requirements Specification Application Map

Requirements Specification is a series of worksheets that list the requirements gathered for the design

Application Map shows the location dependencies between applications Will be used for Flow Analysis


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User RequirementsUser Requirements

The user component of the generic system and the interface:

[ User ] [ User ] /Timeliness---------------------------------------< Interactivity [Application] [Application] \Reliability Quality [ Host ] [ Host ] Adaptability ---------- ---------- Security \----(Network)-----/ Affordability User Numbers User Locations Expected Growth


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User RequirementsUser RequirementsTimeliness “Timeliness is a requirement that the user

is able to access, transfer, or modify information within a tolerable time frame”

What is “tolerable” depends on the user’s perception of the delay in the system EXAMPLES-delays that network will need to

provide: User wants to download files from a server and

complete each transfer in 10 minutes User wants to receive video frames every 30ms

End-to-end or round-trip delay is important measurement


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User RequirementsUser RequirementsInteractivity Similar to “timeliness” but focuses on a

response time from the system or network Interactivity is to be looked as an

indication of the response time which are on the order of the human response times

“Interactivity is a measure of the response time of the system when it is required to actively interact with a human”

The round-trip delay is a measure of the interactivity


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Reliability From the user prospective it is a

requirement for constantly available service Possibility to have access to system

resources a very high percentage of time Consistent level of service to the user in

terms of network performance Thus, reliability as requirement is closely

related to the performance characteristic reliability where delay and capacity are also important


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User RequirementsUser RequirementsQuality Refers to the quality of the presentation

to the user Perception of audio, video and/or data

displays EXAMPLE: Providing videoconferencing,

videofeeds and telephony It is possible to do it on the Internet! But other technologies can provide much

better presentation quality It is often not sufficient to provide just a

capability over a network Measures of quality should include all

the performance characteristics


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User RequirementsUser RequirementsAdaptability “It is ability of the system to adapt to

the user’s changing needs” EXAMPLES:

Distance-independence Relying on the network Coupling to the logical servers and decoupling

from the physical - it does not matter where the servers are as long as users can get services

As a result user may lose a part of his rights - the ability to know where the job was executed

Mobility Mobile computing, access to the services and

resources from any location via portable computers and ad-hoc access to the network

Adaptability must be reflected in the system design


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Security It is a requirement to guarantee

Integrity (accuracy and authenticity) of the user’s information and physical resources

Access to the user’s and system resources

Security is probably closest to the performance characteristic reliability It impacts capacity and delay


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User RequirementsUser RequirementsAffordability It is the last general user requirement

“We would like to have it but how much does it cost?”

Not technical but will impact the network design!

We have to look at the user/customer budget Are design costs too expensive to implement? How cost and funding are tied to users or

groups of users? Funding should be discussed as a system-wide

requirement from the overall budget perspective


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Application Application RequirementsRequirements

We will look at Types of Applications

Reliability Capacity Delay Application Groups

[ User ] [ User ] [Application] [Application] [ Host ] [ Host ] ---------- ---------- \----(Network)-----/


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Types of ApplicationsTypes of Applications

Service and service performance requirements of the applications can be characterized as: Mission-critical applications

Deterministic and/or guaranteed reliability Controlled-rate applications

Specified capacity Real-time/interactive applications

Specified delay


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Types of ApplicationsTypes of Applications User Service and Performance

Requirements Timeliness \_________________ / DELAYInteractivity / \

Reliability \ /Quality \__________________/ RELIABILITYAdaptability / \Security / \

Affordability \ /User Numbers \_____________/ CAPACITYUser Locations / \Expected Growth / \


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Reliability Reliability Reliability can be subjective but some applications must maintain high reliability in order to function Loss of reliability can result in

Loss of revenue or customers Typical application: transaction/money

dependant, investment banking or airline reservation system

Unrecoverable information or situation Telemetry processing and teleconferencing applications

Loss of sensitive data Customer ID/billing and intelligence-gathering

applications Loss of life

Transportation or health-care monitoring applications QUESTION: Can the Best-Effort System be at all suitable

for the mission-critical applications?


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CapacityCapacity Could be required by the applications

having well understood amount of capacity

EXAMPLE: Controlled-rate applications Voice, non-buffered video, some teleservice

applications May require to define:

Thresholds Bounds Guarantees on minimum capacity Peak capacity Sustained capacity

Can be tied to the end-to-end delay of the network


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DelayDelay Optimizing the total (end-to-end and

round-trip) delay is the most important for the application service

Need for “better than the best-effort” services Applications with delay requirements are

migrating to the Internet or IP intranets Applications previously dedicated to a single

user/host are used via Internet/intranet Term “real-time” describes the need for

strict delay tolerance


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DelayDelay Real-time applications Have the most strict timing relationship

between source and destination Timers are set for the receipt of information

If information is received after the timers expire it is considered worthless and is dropped

Does not mean that information has to be transferred within predefined time, rather Delay boundaries (and, hopefully, consequences)

are understood by source and destination Destination does not wait beyond this boundary

EXAMPLE: Video playback - delay beyond the playback timer can cause blank parts in frames


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DelayDelay Non-real-time applications

Various end-to-end delay requirements

Destination will wait until the information is received (defined by the timers in applications and hosts)

Majority of the applications are non-real-time

Can be Interactive

Asynchronous


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DelayDelay Interactive applications Assume timing relationship between

source and destination Typical applications: telnet, FTP, WebAsynchronous applications Intensive to time Assumes no timing relationship

EXAMPLE: E-mail Can be

Burst Bulk


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Application GroupsApplication Groups

It is useful to group together the applications with similar performance characteristics Helps in mapping performance

characteristics Helps in gathering requirements

Groups may have some overlap… EXAMPLES of the groups are

discussed below


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Application GroupsApplication Groups Command and control/telemetry applications

Information is transmitted between remote objects Characterized as having high-performance delay and

reliability Possibly mission-critical and/or real-time applications

Visualization applications Viewing and manipulation of 2-D, 3-D and VR objects Characterized as having high-performance capacity

and delay Possibly real-time and/or controlled-rate applications


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Application GroupsApplication Groups Distributed computing applications

Different variants of the processor coupling Share the same local bus Co-located at the same LAN (computing cluster) Distributed across LAN, MAN, and WAN

boundaries

Degree of distribution/parallelism is also determined by the granularity of the task

Characterized as having high performance delay

Possibly being interactive applications


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Application GroupsApplication Groups Applications for Web access,

development and use Involves accessing remote host and

downloading/uploading information Web-sessions are

Interactive Amounts of information are small

Characterized as being delay-sensitive but NOT high-performance


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Application GroupsApplication Groups Bulk data transport

Typically file transfer (FTP) Optimization of the data transfer rate at the

expense of interactivity Characterized as being not high-performance

Tele-service applications Teleconferencing, telemedicine, teleseminars,…

Simultaneous delivering of mixture of the data, voice, and video to the groups of people at various locations

EXAMPLE: Multicast backbone (mbone) on the Internet

Characterized as having high-performance capacity, delay, and/or reliability, depending on application


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Application GroupsApplication Groups Operations, administration, and

maintenance (OAM) applications Needed for proper functioning and

operation of the network Domain name service (DNS) Mail service/SMTP News services/NNTP Address resolution service (ARP) Network monitoring and management Network security Systems accounting

Generally requires high reliability


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Application GroupsApplication Groups Application Component Interface to

System

[ User ] [ User ] /Application | | / Group [Application] [Application] / Application-----------------------------------------< Type [ Host ] [ Host ] | Application ---------- ---------- | Performance \----(Network)-----/ | Characteristics |Application | Locations


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Host RequirementsHost RequirementsHost Component of the Generic System [ User ] [ User ] | | [Application] [Application] | | [ Host ] [ Host ] ---------- ---------- \----(Network)-----/

We will look at Types of Host and Equipment Performance Characteristics Location Information


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Host RequirementsHost Requirements Types of Host and Types of Host and

EquipmentEquipment Generic computing devices

Dos-, Windows-based PCs, Macs, Unix workstations, etc.

Form access points into the network for [single] user

Important from end-to-end perspective Tend to be overlooked Creates “last foot” problem in systems

performance


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EquipmentEquipment Servers

More powerful Computing servers, storage servers,

application servers, etc. Also have requirements for “last foot”

performance Requirements specific to the server’s role

Specialized Equipment Supercomputers, mainframes, parallel or

distributed computing systems, sensors, data acquisition devices, etc.

Tends to be location-dependent


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EquipmentEquipmentSpecialized Equipment Tends to be Location-

Dependent


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Host RequirementsHost Requirements Performance Performance

CharacteristicsCharacteristics Performance of the components impacts

the overall performance of the server/host

Operating System

Processing

Other Peripherals

Disk DriveNetwork Interface

Memory

System Bus


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Host RequirementsHost Requirements Performance Performance

CharacteristicsCharacteristics Performance of the components end-

to-end in the host is important Storage performance

Disk-drive seek time Tape performance

Processor (CPU) performance Memory performance

Access time System bus performance

Capacity and arbitration mechanisms Effectiveness of Software

Driver OS (effectiveness of the protocol stack)

Number of memory copies in the protocol stack Cost of execution of a given OS

API


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Host RequirementsHost Requirements Location InformationLocation Information

Helps to determine Relationships between components Flow characteristics

Particularly important In the outsourcing of system components

or functions In the consolidation of organizations,

components or functions In the relocation of system components

or functions within an organization


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Host RequirementsHost RequirementsSystem Components can have Location

Dependencies


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Host RequirementsHost RequirementsSummary of the Summary of the

Host/Network InterfaceHost/Network InterfaceHost Component Interface to System

[ User ] [ User ] /Types of | | / Hosts and [Application] [Application] / Equipment | | / [ Host ] [ Host ] / Location ---------- ---------- / Information---------|----------------------|------< \----(Network)----/ \ Host/Equipment \ Performance \ Characteristics


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Network RequirementsNetwork Requirements

Existing Networks and Migration

Functional Requirements

Financial Requirements

Enterprise Requirements


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Network RequirementsNetwork Requirements Existing Networks and Existing Networks and

MigrationMigrationNetwork Component Interface to System

[ User ] [ User ] /-Scaling | | / [Application] [Application] / -Interoperability | | / [ Host ] [ Host ] / -Location Information ---------- ---------- / | | / -Network Services ( Network )--<:…....(<Existing Network> )...: \ -Support Services: / : \:...<Existing Network>…....: \ -Network Performance \ Characteristics


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Network RequirementsNetwork Requirements Functional Functional

RequirementsRequirements Requirements for Network Management

and Security Categories of network management tasks

Monitoring (automatic?) For event notification (frequent snapshot of the

system) For metrics and planning (large archives)

Actions (manual?) Network configuration Troubleshooting

Monitoring: Obtaining values for network management

parameters from network elements Processing the data Visualization Archiving the data


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RequirementsRequirements

General Network Management Requirements Monitoring methods Instrumentation methods

Protocols (SNMP, SNMPv2/v3, CMIP, RMON) Parameter lists (MIBs) Monitoring tools Direct access

The characteristics sets for monitoring In-band vs. out-of-band monitoring Centralized vs. distributed monitoring Performance requirements


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RequirementsRequirements Developing a security plan for the network:

User requirements Security policies Risk analysis

User Requirements for Security Government specified requirements:

MoD/DoD/DoE... Organization-specified security requirements End-user-specified security requirements

May be applied to Users/User groups Projects Specific types of data (also how data are

generated, transferred, processed and stored)


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Network RequirementsNetwork Requirements Financial RequirementsFinancial Requirements

Level of funding for implementing network design is system-wide requirement

Funding is associated with Overall cost limit Recurring components

Expected to occur or be replaced/upgraded periodically

Operations, administrations and maintenance, costs from service providers, provisions for network modification

Non-recurring components - building of the network

Network design Network deployment Hardware/Software components Initial installation or establishment of any services from

service providers


94

Network RequirementsNetwork Requirements Enterprise Enterprise

RequirementsRequirements Enterprises need transfer of

Phone/voice

FAX

Video

Enterprise environment presumes integration of such services into a common transmission infrastructure


95

Requirement AnalysisRequirement AnalysisConclusionsConclusions

The Process Model for Requirement Analysis


96

BibliographyBibliography

• James D. McCabe: “Practical Computer Network Analysis and Design”, Morgan Kaufmann Publishers, San Francisco, USA, 1998. ISBN 1-55860-498-7

• Algirdas Pakštas: Raspredelennye programmnye konfiguracii: Analiz i razrabotka (“Distributed Software Configurations: Analysis and Development”), Mokslas, Vilnius, 1989. ISBN 5-420-00637-5

©2003 algirdas pakštas sisteminis tinklų planavimo metodas bei reikalavimų analizės rolė (nuo...

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